R4
Divisibility Rules
整除性规则
Remainder / 余数Grades G3 - G6
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What It Looks Like
Recognition signals — when you see these, think of this structure:
- 1Questions about whether a number is divisible by 2, 3, 4, 5, 9, etc.
- 2Large numbers where full division is impractical
- 3Finding digits that make a number divisible
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What It Really Tests
The core mathematical idea behind this structure:
Shortcuts to check if a number is divisible by common divisors without full division.
无需完整除法即可检查数字是否被常见除数整除的快捷方式。
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Why Students Get Stuck
Common mistakes to watch out for:
- ⚠Using the wrong rule for the wrong divisor
- ⚠Not simplifying digit sums for divisibility by 3 or 9
- ⚠Forgetting less common rules like divisibility by 6
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Your First Step
How to begin thinking about problems with this structure:
Apply the divisibility test for the specific divisor (sum of digits for 3, last digit for 2, etc.).
应用特定除数的整除性测试（3看数字和，2看末位，等等）。
Related Structures
These structures share similar patterns or thinking approaches: